A number of icons in the Places Library (the "Show all bookmarks" / "Show all history" window) need hidpi versions, so they don't look blurry (upscaled) on Retina displays. * Toolbar button icons (browser/themes/osx/places/toolbar-lion.png) * icons for basically all the items in the sidebar (and when they appear as folders in the list view) * default favicon (dashed outline) for sites * tag icon per list item in Tags view * There are various other small icons without @2x version in browser/themes/osx/places/ and the CSS. Some of these look really old (obsolete / unused?), others may need fixing. Maybe worth a separate bug just to audit / cleanup these icons? * NOTE: site favicons in list are out-of-scope here, as that involves more invasive Places changes needed by multiple things.

Looks like this affects Firefox for Windows too, not just Firefox for OS X. For example, the top left icon in the bookmark mini window (displayed once star toolbar-button is pressed) is currently blurry (tested in latest Beta and Nightly), as well as many icons in the Library window.